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  2. 2. SENSATION the process of receiving stimulus energies from the external environment. sensory organs: eyes (visual system) ears (auditory) nose (olfactory) tongue (gustatory) skin (tactile)
  3. 3. TRANSDUCTION the process of transforming physical energy into electrochemical energy. PE ECE
  4. 4. PERCEPTION the process of organizing and interpreting sensory information to give it meaning. Prior experiences Expectations Memory Biases
  5. 5. BOTTOM-UP PROCESSING Processing that begins with sensory receptors registering environmental information and sending it to the brain for cognitive processing and integration. TOP-DOWN PROCESSING Processing of perpetual information that starts out with cognitive processing at the higher levels of the brain.
  7. 7. Why is it important to study sensation and perception? The purpose of perception is: 1) to represent information from the outside world internally; 2) adaptation that improves a species’ chances for survival; and 3) to help in designing devices to restore perception to those who have lost some (or all) and also to devise treatments for other perceptual problems.
  8. 8. SENSORY RECEPTORS All sensation begins with sensory receptors. Sensory receptors are specialized cells that detect and transmit stimulus information to sensory nerves and the brain.
  9. 9. 3 Classes of SENSORY RECEPTORS 1.Photo reception(detection of light, perceived as sight.) 2.Mechanoreception (detection of pressure, vibration, and movement perceived as touch, hearing and equilibrium.) Chemoreception (detection of chemical stimuli detected as smell and taste. 3.
  10. 10. How close does an approaching bumblebee have to be before you can here its buzzing? Difference between a ‘Coke’ and a ‘Coke Zero’? The percentage of fat in a ‘low fat’ and a regular milk?
  11. 11. THRESHOLD A level or point at which something starts or ceases to happen or come in to effect.
  12. 12. SENSORY THRESHOLDS Absolute Threshold Orange juice One tablespoon? Two tablespoon? Three tablespoon! -Watching TV while your roommate is sleeping. Volume? -
  13. 13. SENSORY THRESHOLDS Absolute threshold - Minimum amount of energy that a person can detect. Difference threshold - just noticeable difference (jnd) the degree of difference that must exist between two stimuli before the difference is detected.
  14. 14. Percent of yes responses 120 100 80 60 40 20 0 30 25 20 15 10 5 Distance in feet from an alarm clock. 0
  15. 15. Approximate Absolute Thresholds Vision A candle flame at 30 miles on a dark, clear night. Hearing A ticking watch at 20 feet under quiet conditions. Smell One drop of perfume diffused throughout 3 rooms Taste A teaspoon of sugar in 2 gallons of water Touch The wing of a fly falling on your cheek from a distance of one centimeter. -
  16. 16. Difference Threshold Watching TV while your roommate is sleeping. Your roommate, suddenly wakes-up. Also wants to watch the TV! Volume? -
  17. 17. JND! No JND! 2 4 6 9 1213
  18. 18. A student late for his class. 10: 03 – late? 10:05 – late? 10: 10 – late? 10:15 – late!!! It takes 15 minutes for a student to be detected as late. Absolute or difference threshold? *Depends on the individual who perceives and the condition of the environment.
  19. 19. WEBER’S LAW The principle that two stimuli must differ by a constant minimum percentage to be perceived as different.
  20. 20. Subliminal Perception -the ability to detect information below the level of conscious awareness.
  21. 21. SIGNAL DETECTION THEORY The theory that focuses on decision making about stimuli in the presence of uncertainty; detection depends on a variety of factors beside the physical intensity of the stimulus and the sensory abilities of the observer.
  22. 22. PERCEIVING SENSORY STIMULI A.Attention Selective Attention— focusing on a specific aspect of experience while ignoring others.
  23. 23. B. Perceptual Set a predisposition, or readiness, to perceive something in a particular way. Sensory Adaptation A change in the responsiveness of the sensory system based on the average level of surrounding stimulation.
  24. 24. CHARACTERISTICS of LIGHT THE EYE! 1.Wavelength- distance from LIGHT of one wave to the the peak next. of electromagnetic form 2. energy that can be Hue- color 3. described in terms of a Amplitude- the height of wave. wavelength; travels 4.Purity- the mixture of through space in waves. wavelengths in light.
  25. 25. COLOR TREE
  26. 26. PARTS OF THE EYE SCELERA the white outer part of the eye that helps maintain the shape and protects from injury.
  27. 27. IRIS the colored part of the eye, contains muscle that control the size of the pupil, hence, the amount of light that enters.
  28. 28. PUPIL appears black, and is the opening in the center of the iris.
  29. 29. The light sensitive surface in the back of the eye that houses light receptors. A transparent, flexible, disklike gelatinous material. Use to bend light on the eye. A minute area in the center of the retina which vision is at its best. It’s the place on the retina where the optic nerve leaves the on its way to the brain. A clear membrane just in front of the eye.
  30. 30. VISUAL CORTEX located in the occipital lobe of the brain. Visual information processing involves feature detection, parallel processing and binding. Feature Detectors (David Hubel&Torsten Wiesel) neurons of the brain’s visual system that respond to particular lines or other features of a stimulus. A.
  31. 31. PARALLEL PROCESSING 1.What Pathway processes information about what the object is, its color, form and its texture; temporal lobe. Where Pathway processes information on an object’s location, movement, depth of the object; parietal lobe. 2.
  32. 32. BINDING The bringing together and integration of what is processed by different pathways or cells.
  33. 33. TRICHROMATIC THEORY (THOMAS YOUNG 1802) (ex: HERMANN von HELMONTZ 1852) Color perception is based on the existence of three of color receptors that are maximally sensitive to different, but overlapping ranges wavelengths.
  34. 34. COLOR VISION 1.Trichromatic theory Color perception is based on the existence of three color receptors that are maximally sensitive to different, but overlapping, ranges of wavelengths.
  35. 35. A.Dichromats people with only two kinds of cones. B.Trichromats have three kinds of cone receptors and normal vision. C.Afterimages- sensations that remain after a stimulus is removed. OPPONENT-PROCESS Theory Cells in the visual sys. respond to green and blue-yellow colors; a given cell might be excited be red and inhibited by green, whereas another might be excited by yellow and inhibited by blue.
  36. 36. Sensory adaptation The sensory receptor cells become less responsive to an unchanging stimulus. The receptors are no longer sending signals to the brain. - Habituation - The sensory receptor cells are still responding to the stimulus, but the lower centers of the brain are not sending the signals from those receptors in the cortex.
  37. 37. QUESTIONS?